Ceramic composite material

ABSTRACT

A process for manufacturing ceramic-metal composite material, comprises dissolving ceramic powder into water to obtain an aqueous solution of ceramic; mixing metal powder having a multimodal particle size where largest particle size is one fourth of the minimum dimension of a device, with the aqueous solution of ceramic to obtain a powder containing ceramic precipitated on the surface of metal particles; mixing the powder containing ceramic precipitated on the surface of the metal particles, with ceramic powder having a particle size below 50μιτι, to obtain a powder mixture; adding saturated aqueous solution of ceramic to the powder mixture to obtain an aqueous composition containing ceramic and metal; compressing the aqueous composition to form a disc of ceramic-metal composite material containing ceramic and metal; and removing water from the ceramic-metal composite material; wherein ceramic content of the disc is 10 vol-% to 35 vol-%. Alternatively, ceramic-ceramic composite material may be manufactured.

This application is the U.S. national phase of International ApplicationNo. PCT/FI2018/050518 filed 28 Jun. 2018, which designated the U.S. andclaims priority to FI Patent Application No. 20175635 filed 30 Jun.2017, the entire contents of each of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The invention relates to a ceramic composite material, and moreparticularly to preparation of such material.

BACKGROUND

Ceramic materials are used in a wide range of industries, includingmining, aerospace, medicine, refinery, food and chemical industries,packaging science, electronics, industrial and transmission electricity,and guided lightwave transmission. In composite materials made frommetal and ceramics, a metallic substrate material is reinforced withceramic hardened particles. This makes it possible to combine the lowweight of the metal with the resistance of ceramics. Ceramic compositematerials may be used for the manufacture of electronic components.Electronic components may be active components such as semiconductors orpower sources, or passive components such as resistors or capacitors.

SUMMARY

According to an aspect, there is provided the subject matter of theindependent claims. Embodiments are defined in the dependent claims.

One or more examples of implementations are set forth in more detail inthe description below. Other features will be apparent from thedescription and from the claims.

DETAILED DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplary. Although the specification mayrefer to “an”, “one”, or “some” embodiment(s) in several locations, thisdoes not necessarily mean that each such reference is to the sameembodiment(s), or that the feature only applies to a single embodiment.Single features of different embodiments may also be combined to provideother embodiments. Furthermore, words “comprising”, “containing” and“including” should be understood as not limiting the describedembodiments to consist of only those features that have been mentionedand such embodiments may contain also features/structures that have notbeen specifically mentioned.

Li₂MoO₄ ceramics may be prepared at room-temperature based onutilization of a small amount of water with Li₂MoO₄ powder. Thedensification of the ceramic takes place by pressing and removal ofexcess water. Thus the shape and size of the ceramic object may beadjusted by controlling the mould dimensions and the amount of ceramicmaterial. Post-processing may be applied at 120° C. to remove residualwater from the object. However, the post-processing step is notmandatory, or the post-processing step may performed at a temperaturelower than 120° C. The dielectric properties obtainable by the lowtemperature ceramic material may be similar to those achieved forLi₂MoO₄ ceramics fabricated by sintering at 540° C. (e.g. relativepermittivity of 5.1, and a loss tangent value of 0.00035 at 9.6 GHz).

In an embodiment, the ceramic composite material contains lithiummolybdate Li₂MoO₄.

In an embodiment, instead of or in addition to lithium molybdateLi₂MoO₄, the ceramic composite material may contain NaCl, Na₂Mo₂O₇,K₂Mo₂O₇, (LiBi)_(0.5)MoO₄, KH₂PO₄, Li₂WO₄, Mg₂P₂O₇, and/or V₂O₅, forexample.

Lithium molybdate Li₂MoO₄ may be used as a raw material to prepare theceramic composite material. The raw material may be argillaceous(clayish) material, paste, slurry, or a less viscous fluid that enablesforming or molding of the material according to an embodiment.

The process for the manufacture of an electronic component comprisingthe ceramic composite material containing lithium molybdate, may includepressure molding (press molding), molding (slip casting), dipping, or2D/3D printing (two-dimensional or three-dimensional printing).

Thus an embodiment discloses an electronic component comprising anelectronic component comprising ceramic composite material containinglithium molybdate Li₂MoO₄. The electronic component may comprise atleast one of a battery, an electrical connection path, and conditioningelectronics.

An embodiment relates to ceramic-metal composites. Another embodimentrelates to ceramic-ceramic composites. Ceramic materials are extremelydurable and stable as such. The characteristics of the ceramic materialmay be changed by adding metals or another type of ceramic to theceramic matrix material. Metals typically are tensile and durablematerials and have a high thermal conductivity. Ceramics typically arechemically stable and inoxidizable, and they have a high meltingtemperature. An exemplary ceramic-metal composite enables combining theoptimum characteristics of both the metal(s) and the ceramic(s), such asthe hardness and high thermal strength of the ceramic(s), and theconductivity of the metal(s). An exemplary ceramic-ceramic compositeenables combining the optimum characteristics of different ceramicmaterials, such as versatile electrical and magnetic performances,including ferroelectric, pyroelectric, piezoelectric, ferrite, highdielectric and ferromagnetic characteristics.

An exemplary ceramic-metal composite material may be used formanufacturing of electronic components such as resistors, capacitors andother electronic components. Exemplary ceramic-metal composite materialsmay also be used in machine tools to substitute metal blades. Exemplaryceramic-ceramic and/or ceramic-metal composite materials may also beused in sensors to substitute conventional high temperaturepiezoelectric ceramics, and magnetic materials in ferrite applications,such as the core of the coils. Exemplary ceramic-metal composites and/orceramic-ceramic composites may also be used at ceramic-metal interfaces,in biomedicine, as friction materials in brakes, in optoelectroniccomponents, and/or as splinterproof in armoured vehicles.

An exemplary ceramic-ceramic composite material may be used formanufacturing of electronics components, such as capacitors, coils,sensors, actuators, high frequency passive devices, energy storage andharvesting, tuning elements and transformers.

An advanced ceramic-metal composite material and a method formanufacturing the advanced ceramic-metal composite material aredisclosed. Further, an advanced ceramic-ceramic composite material and amethod for manufacturing the advanced ceramic-ceramic composite materialare disclosed. Exemplary ceramic-metal and ceramic-ceramic compositematerials may be used for the production of resistors, capacitors and/orconductors in low temperature manufacture of electronics (e.g. printedelectronics). The low temperature (e.g. room temperature) manufactureenables an energy saving manufacture of the electronic component. In thelow temperature manufacture, diffusion between the metal and ceramicphases does not occur or is minimal, which enables improving theelectrical properties of the material as the ceramic and the metalmaintain their original dielectric, ferroelectric and magneticproperties. Thus, the formation of additional phases of e.g. lossymaterial may be prevented or reduced.

An embodiment discloses a process for manufacturing ceramic-metalcomposites. Another embodiment discloses a process for manufacturingceramic-ceramic composites. The ceramic contains, for example, lithiummolybdate (Li₂MoO₄) which crystallizes at room temperature. Insteadof/in addition to lithium molybdate, the ceramic may contain NaCl,Na₂Mo₂O₇, K₂Mo₂O₇, (LiBi)_(0.5)MoO₄, KH₂PO₄, Li₂WO₄, Mg₂P₂O₇, and/orV₂O₅, for example. The ceramic-metal composite contains metal particles(e.g. Al, Fe, Ni, Co, Ag, Cu, Tb_(x)Dy_(1-x)Fe₂, NdFeB, SmCo₅, and/orother elements or alloys that enable obtaining the required thermal,electrical and/or magnetic functionalities) as additives. Theceramic-ceramic composite contains ceramic particles (e.g. PZT,Ba_(x)Sr_(1-x)TiO₃, TiO₂, Al₂O₃, KNBNNO and related, ferrites andrelated, and/or other electroceramic materials).

An exemplary process for manufacturing ceramic-metal or ceramic-ceramiccomposites comprises preparing metal or ceramic powder having amultimodal particle size where the largest particle size is one fourthof the minimum dimension of the electronic device. The process furthercomprises dissolving Li₂MoO₄ powder into water to obtain an aqueoussolution of Li₂MoO₄. The metal or ceramic powder is mixed with theaqueous solution of Li₂MoO₄.

A powder is thus obtained, containing Li₂MoO₄ precipitated on thesurface of the metal or ceramic particles, which powder is mixed withlithium molybdate having a particle size below 50 μm. The powder thuscontains Li₂MoO₄ in water, Li₂MoO₄ particles as mentioned above andmetal or ceramic particles producing the electrical functionality. Theamount of Li₂MoO₄ in the ceramic-metal or ceramic-ceramic composite isfrom 10 to 30 vol-% compared to metal or ceramic material. For example,0.1-0.5 ml of saturated aqueous solution of Li₂MoO₄ is then added to0.8-1.2 g of the powder mixture to obtain a composition. The compositionthus obtained is then compressed in a mould (e.g. in a 10 mm diametermould) by using a moulding pressure of e.g. 250 MPa to form a soliddisc. The water content of the composition/the disc after thecompression moulding is to be 2.5-3.0 wt-%. A water content above 3 wt-%may make the handling of the discs difficult. The Li₂MoO₄ content of thefinal product may be 14-35 vol-%.

The discs may be dried in an oven for 16 h at a temperature of 120° C.to remove water residual. Alternatively, the discs may be dried at roomtemperature, or at any temperature from 20° C. to 120° C., but in thatcase a longer drying time is required. After drying, the surfaces of thediscs are polished to remove adhered impurities and to obtain a smoothsurface for the electrodes. The electrodes may then be prepared on thedisc surface by using silk screen printing ink, for example.

Thus an exemplary process for manufacturing ceramic-metal orceramic-ceramic composites comprises using metal or ceramic particleshaving a multimodal particle size (e.g. below 180 μm) where the largestparticle size is one fourth of the minimum dimension of the electronicdevice, and lithium molybdate particles having a small particle size(i.e. below 50 μm), wherein a saturated aqueous solution of Li₂MoO₄, andcompression moulding in an anti-adhesive mould at a pressure of 250 MPa,are used to obtain the discs. Alternatively 3D printing may be used toobtain the discs. The ceramic-metal and ceramic-ceramic composites areusable in various applications including electronics applications suchas materials used in printed electronics. The ceramic-metal compositesmay be thermally conductive, and have a high thermal strength and a widerange of properties typical for electroceramics.

In an embodiment, instead of or in addition to lithium molybdateLi₂MoO₄, the ceramic-metal or ceramic-ceramic composite material maycontain NaCl, Na₂Mo₂O₇, K₂Mo₂O₇, (LiBi)_(0.5)MoO₄, KH₂PO₄, Li₂WO₄,Mg₂P₂O₇, and/or V₂O₅, for example.

A process for manufacturing the ceramic-metal composite material,comprises dissolving Li₂MoO₄ or other ceramic powder into water toobtain an aqueous solution of Li₂MoO₄ or said other ceramic; mixingmetal powder having a multimodal particle size where largest particlesize is one fourth of the minimum dimension of an electronic device,with the aqueous solution of Li₂MoO₄ or other ceramic to obtain a powdercontaining Li₂MoO₄ or said other ceramic precipitated on the surface ofmetal particles; mixing the powder containing Li₂MoO₄ or said otherceramic precipitated on the surface of the metal particles, with Li₂MoO₄or said other ceramic powder having a particle size below 50 μm, toobtain a powder mixture; adding saturated aqueous solution of Li₂MoO₄ orsaid other ceramic to the powder mixture to obtain an aqueouscomposition containing Li₂MoO₄ or said other ceramic, and metal;compressing the aqueous composition in a mould by using a mouldingpressure, to form a disc of ceramic-metal composite material containingLi₂MoO₄ or said other ceramic, and metal; drying the disc to removewater from the ceramic-metal composite material; wherein Li₂MoO₄ or saidother ceramic content of the disc is 10 vol-% to 35 vol-%.

The metal comprises Al, Fe, Ni, Co, Ag, Cu, Tb_(x)Dy_(1-x)Fe₂, NdFeB,SmCo₅, and/or other metal element or metal alloy.

Said other ceramic contains at least one of NaCl, Na₂Mo₂O₇, K₂Mo₂O₇,(LiBi)_(0.5)MoO₄, KH₂PO₄, Li₂WO₄, Mg₂P₂O₇, and V₂O₅.

A process for manufacturing ceramic-ceramic composite material,comprises dissolving first ceramic powder containing Li₂MoO₄ or otherceramic, into water to obtain an aqueous solution of a first ceramic;mixing second ceramic powder having a multimodal particle size wherelargest particle size is one fourth of the minimum dimension of anelectronic device, with the aqueous solution of the first ceramic toobtain a powder containing first ceramic precipitated on the surface ofsecond ceramic particles; mixing the powder containing first ceramicprecipitated on the surface of the second ceramic particles, with thefirst ceramic powder having a particle size below 50 μm, to obtain apowder mixture; adding saturated aqueous solution of the first ceramicto the powder mixture to obtain an aqueous composition containing thefirst and second ceramic; compressing the aqueous composition in a mouldby using a moulding pressure, to form a disc of ceramic-ceramiccomposite material containing first and second ceramic; drying the discto remove water from the ceramic-ceramic composite material; whereinfirst ceramic content of the disc is 10 vol-% to 35 vol-%.

The first ceramic contains at least one of Li₂MoO₄, NaCl, Na₂Mo₂O₇,K₂Mo₂O₇, (LiBi)_(0.5)MoO₄, KH₂PO₄, Li₂WO₄, Mg₂P₂O₇, V₂O₅ The secondceramic contains at least one of PZT, Ba_(x)Sr_(1-x)TiO₃, TiO₂, Al₂O₃,KNBNNO and related, ferrites and related, and other electroceramicmaterial. The first and second ceramic are different from each other.

The compressing of the aqueous composition may be performed by using amoulding pressure of 100 to 500 MPa, preferably 250 MPa.

The disc may be dried for at least 16 h at a temperature from 20° C. to120° C., preferably for 16 h at a temperature of 120° C.

After drying, the surface of the disc may be polished to obtain a smoothdisc surface, wherein electrodes are prepared on the smooth disc surface(e.g. by printing).

The ceramic-metal composite material may have a ceramic content of 10vol-% to 35 vol-%, and comprises metal powder having a multimodalparticle size where largest particle size is one fourth of the minimumdimension of an electronic device (electronic component). Theceramic-metal composite material is obtainable by the above process.

The ceramic-ceramic composite material may have a first ceramic contentof 10 vol-% to 35 vol-%, and comprises second ceramic powder having amultimodal particle size where largest particle size is one fourth ofthe minimum dimension of an electronic device (electronic component).The ceramic-ceramic composite material is obtainable by the aboveprocess.

An electronic component is disclosed, comprising the ceramic-metal orceramic-ceramic composite material. The electronic component maycomprise at least one of a resistor, conductor and capacitor.

The ceramic-metal or ceramic-ceramic composite material may be used inelectronic components, such as resistors, capacitors, coils, sensors,actuators, high frequency passive devices, energy storage andharvesting, tuning elements and/or transformers.

An electronic product is disclosed, comprising the electronic component.

The particle size of the second ceramic powder may be above 50 μm. Thisenables maximizing the amount of second ceramic powder in the compositematerial. The amount of the second ceramic powder in the compositematerial may be above 65 vol-%. Thus the second ceramic powder may bethe dominant element in the composite.

The second ceramic powder may be formed of insoluble metal/ceramic, andmore than 65 vol-% of the composite material may be formed of the secondceramic powder.

The particle size distribution of the insoluble particles is multimodal,wherein the largest particles have a particle size of more than 50 μm.This enhances the filling of the mould and preparation of the disc.

The temperature in the process for manufacturing the composite materialdoes not exceed 150° C., nor does it need to exceed the boilingtemperature of the solution. No extra heating is required in the processduring the compressing, instead the compression may be performed at aroom temperature. Optional heat treatment may be performed after thecompressing and compacting of the disc. The process time to prepare thedisc may be only 2 to 5 min.

It will be obvious to a person skilled in the art that, as thetechnology advances, the inventive concept can be implemented in variousways. The invention and its embodiments are not limited to the examplesdescribed above but may vary within the scope of the claims.

The invention claimed is:
 1. A process for manufacturing ceramic-metalcomposite material, the method comprising: obtaining an aqueous solutionof ceramic by dissolving powder of said ceramic into water; obtaining apowder containing said ceramic precipitated on a surface of metalparticles by mixing metal powder with said aqueous solution of ceramic,the metal powder having a multimodal particle size where largestparticle size is above 50 μm and less than 180 μm; obtaining a powdermixture by mixing said powder containing said ceramic precipitated onthe surface of metal particles, with powder of said ceramic having aparticle size below 50 μm; obtaining an aqueous composition containingsaid ceramic, and metal, by adding saturated aqueous solution of saidceramic to the powder mixture; forming a disc of ceramic-metal compositematerial containing said ceramic, and metal, by compressing the aqueouscomposition in a mould; removing water from the ceramic-metal compositematerial by drying the disc; wherein the content of said ceramic is 10vol-% to 35 vol-% in the disc, wherein the content of said metal isabove 65 vol-% in the disc, and wherein said ceramic contains at leastone of Li₂MoO₄, Na₂Mo₂O₇, K₂Mo₂O₇, (LiBi)_(0.5)MoO₄, Li₂WO₄, Mg₂P₂O₇,and V₂O₅.
 2. A process according to claim 1, wherein the metal comprisesone or more of Al, Fe, Ni, Co, Ag, Cu, Tb_(x)Dy_(1-y)Fe₂, NdFeB, andSmCo₅.
 3. A process according to claim 1, wherein the compressing of theaqueous composition is performed by using a moulding pressure of 100 to500 MPa.
 4. A process according to claim 1, wherein the disc is driedfor at least 16 h at a temperature from 20° C. to 120° C.
 5. A processaccording to claim 1, wherein after drying, the surface of the disc ispolished to obtain a smooth disc surface, wherein electrodes areprepared on the smooth disc surface.
 6. A process according to claim 1,wherein after drying, the surface of the disc is polished to obtain asmooth disc surface, wherein electrodes are prepared on the smooth discsurface by printing.
 7. A process according to claim 1, wherein thecompressing of the aqueous composition is performed by using a mouldingpressure of 250 MPa.
 8. A process according to claim 1, wherein the discis dried for 16 h at a temperature of 120° C.